1. Field of the Invention
This invention relates to flatbed trailers which are adapted for hauling frangible sheet material and are towed by tractors over roads and highways. More particularly, the invention relates to a trailer structure which includes a glass-supporting apparatus mounted on a specially designed flatbed trailer and adapted to support loads of uncrated sheet glass, commonly known as "stolz" glass of various length and thickness. The trailer structure is also capable of carrying crated sheet glass of various dimension, as well as other frangible sheet material, such as concrete panels. The support apparatus in the trailer structure of this invention is designed to maintain the sheets of glass in a nearly upright position in order to prevent undue stressing of the glass and to keep both the dimensions of the trailer structure and the glass or other frangible material itself within the legal height and width regulations promulgated by the various governing bodies.
It is frequently desirable to transport multiple, large sheets of glass from a manufacturing facility to various dealers and user locations, where it is unloaded and cut to specification. The glass is initially fabricated in large sheets and is very brittle; as such, it must be transported in a nearly vertical position in order to prevent cracking and breaking due to stress. Maintaining such large glass sheets within the legal height and width regulations of the various regulatory bodies makes it difficult to design a transporting apparatus which will minimize cracking and breaking of the glass. The glass must also be protected from the elements during transportation, since water seepage into the interfaces between the glass sheets makes it virtually impossible to separate the sheets without breaking the glass during unloading.
Sheet glass is normally manufactured by a continuous casting float process and as it cools and solidifies, it is cut while in motion to various lengths. While the glass can be cut to substantially any desired length, the brittle and fragile nature of the material restricts the practical size and the largest dimension to which it is cut is normally 130".times.204". The sheets of glass are then sold and transported to dealers and fabricators and are cut to various sizes, depending on the requirements of customers, at the points of destination. It is the general practice of sheet glass dealerships to stock an inventory of large bulk sheets of glass for this purpose.
2. Description of the Prior Art
There are currently three basic methods of transporting large sheets of glass from one point to another. The first method involves installing removable racks on trailers of proper design configuration, which racks serve to maintain the glass in a nearly vertical orientation. These racks are usually elaborate in design, very expensive, and multiple problems are associated in transporting glass by this technique. First of all, the difficulty of fastening the racks to the trailer in a safe manner is presented. Secondly, the expense of the racks makes it mandatory that they be returned to the shipping point, a procedure which involves additional labor and is expensive. Another problem with this technique of transporting glass is found in the requirement that the trailer to which the racks are attached must be able to twist and stress as the tractor turns and travels over uneven road surfaces. This twisting and bending effect is transferred to the racks and to the glass itself, adding stress which frequently causes the racks to pull loose in the trailer and break the glass. If the racks tilt or the glass cracks, a very dangerous situation is presented and the receiver of the broken glass will normally refuse to unload because of the danger to employees. Accordingly, under such circumstances the load must be transported in a disposal site and removed from the trailer with a crane in order to minimize danger from flying glass shards, even if only one sheet of glass is broken in the load. One advantage in transporting glass with removable racks is the option of transporting other goods and commodities after the glass is delivered and the racks are dismantled from the trailer. However, this option presents the shipper and consignee with the problem and expense of removing, collapsing and storing the racks, as well as shipping the racks back to the point of origin, an expense which frequently overrides the multiple load economic advantage.
A second method of shipping large sheets of glass consists of crating the glass in wood and building wooden A-frames to support the crates in a nearly vertical position. However, all crating and framing material must be discarded at the point of destination, a mandate which requires additional labor and expense. Furthermore, the framing material frequently fails as it is stressed by the twisting, turning and bending of the trailer which results from travel over the roads and highways. Another problem which is inherent in the building of the frames and crates with the glass sheets in place is that of striking the glass with a nail or nails during the crating process and breaking the glass, which breakage may be unnoticed until the glass arrives at its destination.
The third major method of transporting large sheets of glass is on trailers having a certain design configuration which features A-frames built into the trailer itself. Due to this A-frame constructure, the racks must be built in a very sturdy manner to minimize the twisting, turning and bending road effect as the trailer travels around corners and over uneven road and highway surfaces. Furthermore, both the trailer and the rack are subjected to severe stresses as the trailer frame deflects and twists during travel, and such trailers are very heavy, a factor which sometimes limits the legal load-carrying capacity of the trailers. Additionally, these specially designed trailers are normally further limited, in that they are able to carry sheets of glass only, and cannot normally be used to transport other cargo. Accordingly, the transporter must charge a much higher rate in order to compensate for the poor utility of these trailers, although this type of trailer does eliminate the requirement of disposable racks, frames and in-situ fabricated crates, and therefore realizes a lower glass breakage rate. However, occasional breakage is still realized because of the road stresses involved in transporting the glass.
Typical of the early vehicles for carrying plate glass is the "Plate Glass Carrying Truck" disclosed in the U.S. Pat. No. 2,100,971, dated Nov. 30, 1937, to J. M. McDonald. This patent details a truck or vehicle which contains racks that are carried in a nearly vertical position and can be swung inwardly against the side of the truck body when not used to carry the glass. U.S. Pat. No. 2,681,233, dated June 15, 1954, to W. C. Smith, discloses a "Rack for Removing Glass Case Fronts". This patent details an easel-type rack for temporarily supporting a plate-glass front, for example in a museum showcase, in order to permit the substitution of new exhibits and cleaning of the glass interface by one person. A "Rack for Plate-Glass", is disclosed in U.S. Pat. No. 2,815,861, dated Dec. 10, 1957, to O. L. Shodorf, Sr. The Shodorf rack includes a support device which will receive and support plate-glass on edge and in a slightly leaning position. The rack is constructed of vertically adjustable upper and lower sections, which adjustment is accomplished by means of a gear and rack mechanism associated with the rack. A brake unit automatically locks the rack in any expanding or contracted position to which it is adjusted. U.S. Pat. No. 3,848,917, dated Nov. 19, 1974, to John L. O'Neil, discloses an "Apparatus for Transporting Flat Glass and the Like". This apparatus is designed as a structure for semi-trailers and is used for transporting large sheets of flat, rigid material such as flat glass. A generally A-shaped platform having a central web is secured over a conventional semi-trailer frame. The platform includes multiple, rigid girders extending from a horizontal top bar downwardly on each side of the truck frame to provide a central, sloped support wall. The central web within the wall rests upon the truck frame to support the entire unit. A platform support extends from the lower end of the support wall on each side at a level below the truck frame, to provide a floor for supporting the lower edges of the glass sheets which lean against the support wall. Extensible clamping means is provided to clamp a stack of glass sheets against the support wall and hold the stack against movement during transit. An "Apparatus for Transporting Glass Sheets and the Like" is disclosed in U.S. Pat. No. 4,195,738, to John O'Neil. This apparatus is characterized by an improved device by carrying stacks of large glass sheets for over-the-road movement. The device includes a main truck-trailer frame having a floor and a generally vertical central support for carrying one or more large sheets of glass in a generally vertical position. A fixed guide-bar extends the length of the frame behind the central support and laterally extending rails are removably secured to the guide-bar adjacent the opposed vertical edges of the sheet. A longitudinal rail is adjustably secured to the outer ends of the lateral rails to extend across the outer face of the sheets and means are provided to draw both the lateral and longitudinal rails against the glass sheets to hold it securely against movement. A specially designed bracket is used to secure the lateral rails to the fixed guide-bar and longitudinal rail and provide for vertical adjustment of the height of the lateral and longitudinal rails to accommodate glass sheets of various size.
It is an object of this invention to provide a trailer-mounted support apparatus for supporting sheet glass and other brittle material, which apparatus includes in a first preferred embodiment, a fixed upright structure characterized by an A-frame rack rigidly attached to the primary load-carrying beams of a trailer chassis, with a second glass-carrying saddle rack straddling the rigid A-frame and pivoting like a pendulum on the rigid A-frame rack to minimize road stress.
Another object of the invention is to provide a sheet glass support apparatus which includes a pair of A-frames situated on a drop frame trailer chassis, the first of which A-frames is fixedly secured to the chassis and the second, glass-carrying A-frame designed to "float" or pivot in pendulum fashion on the first A-frame, to facilitate a stress-relieving action for the glass.
Still another object of the invention is to provide a trailer structure for transporting sheet glass and other brittle material, which trailer structure is characterized by a specially designed trailer chassis having a lowered undercarriage and pivoting deck panels and a support apparatus characterized by a first A-frame fixedly attached to the trailer chassis and a second, brittle material-supporting A-frame pivotly saddled to the first A-frame and extending through the undercarriage for carrying multiple sheets of frangible material, with cushion means disposed between the first A-frame and the second A-frame or the trailer chassis to facilitate dampened pendulum movement of the second A-frame, in order to minimize or prevent torsion, bending, linear and oscillating stress in the frangible material during transportation.
Still another object of the invention is to provide a new and improved support apparatus and trailer chassis combination for transporting sheet glass and other brittle material, which resulting trailer structure is characterized by a fixed A-frame mounted on a specially designed drop frame trailer chassis having pivoting deck panels, a movable A-frame saddled or pivotly attached to the fixed A-frame at the apex ridge of the fixed A-frame for carrying multiple glass sheets, with cushioning means, such as air bags, coil springs and/or air or hydraulic cylinders, located between the first A-frame and the second A-frame, or between the second A-frame and the trailer chassis, in order to facilitate movement of the second A-frame and the glass in a pendulum motion with respect to the first A-frame, responsive to operation of the trailer and minimize or eliminate twisting, bending, linear and oscillating stresses in the glass or other material during transportation.
A still further object of this invention is to provide a new and improved support apparatus and modified trailer chassis for transporting sheet glass, which resulting trailer structure is characterized by a trailer chassis having a narrow center section for receiving a supporting A-frame in fixed relationship, with a glass-supporting saddle frame pivotedly attached to and cushioned on the apex ridge of the fixed A-frame and extending through a lowered undercarriage in the trailer chassis, in order to transport sheets of glass in an upright position and minimize stresses in the sheet glass. The trailer chassis further includes hinged deck sections mounted on the trailer to facilitate loading and unloading the glass and transportation of other goods along with, or in place of the sheet glass.